/* ============================================
   MD3 App Shell & Layout
   ============================================ */
.app {
  display: flex;
  flex-direction: column;
  height: 100vh;
  height: calc(var(--vh, 1vh) * 100);
  min-height: -webkit-fill-available;
  max-width: var(--app-max-width);
  margin: 0 auto;
  background: var(--md-sys-color-surface);
  overflow: hidden;
  padding-top: var(--safe-top);
  padding-left: var(--safe-left);
  padding-right: var(--safe-right);
  position: relative;
}

.app-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  min-height: 0;
}

.chat-container {
  flex: 1;
  display: flex;
  flex-direction: column;
  height: 100%;
  min-height: 0;
}

/* ---- Message List (MD3 Surface) ---- */
.message-list {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding: 12px 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  background: var(--md-sys-color-surface);
  scroll-behavior: smooth;
  -webkit-overflow-scrolling: touch;
  overscroll-behavior: contain;
}

.message-list::-webkit-scrollbar { width: 4px; }
.message-list::-webkit-scrollbar-track { background: transparent; margin: 4px 0; }
.message-list::-webkit-scrollbar-thumb {
  background: var(--md-sys-color-outline-variant);
  border-radius: var(--md-sys-shape-corner-full);
  min-height: 30px;
}
.message-list::-webkit-scrollbar-thumb:hover {
  background: var(--md-sys-color-outline);
}

@media (prefers-color-scheme: dark) {
  .message-list::-webkit-scrollbar-thumb {
    background: rgba(255,255,255,0.15);
  }
}

/* ---- Input Container (MD3 Surface Container) ---- */
.input-container {
  border-top: 1px solid var(--md-sys-color-outline-variant);
  padding: 8px 12px;
  background: var(--md-sys-color-surface-container-low);
  position: sticky;
  bottom: 0;
  z-index: var(--z-sticky);
  display: flex;
  align-items: center;
  padding-bottom: calc(8px + var(--safe-bottom));
  transform: translateZ(0);
}

/* ---- Loading States ---- */
.loading {
  text-align: center;
  color: var(--md-sys-color-on-surface-variant);
  padding: 48px 32px;
  font-size: var(--md-sys-typescale-body-medium-size);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.loading-spinner {
  font-size: 24px;
  animation: spin 1s linear infinite;
  color: var(--md-sys-color-primary);
}

.empty-state {
  text-align: center;
  color: var(--md-sys-color-on-surface-variant);
  padding: 64px 32px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  animation: fadeIn 300ms var(--md-sys-motion-easing-emphasized-decelerate);
}

.empty-icon {
  font-size: 56px;
  opacity: 0.6;
  margin-bottom: 4px;
}

.empty-state p {
  font-size: var(--md-sys-typescale-body-medium-size);
  color: var(--md-sys-color-on-surface-variant);
  margin: 0;
  line-height: var(--md-sys-typescale-body-medium-line);
}

.empty-state .empty-hint {
  font-size: var(--md-sys-typescale-body-small-size);
  color: var(--md-sys-color-outline);
  margin-top: 4px;
}

/* ---- Connection Status (MD3 Badge) ---- */
.connection-status {
  position: fixed;
  top: 8px;
  right: 8px;
  z-index: var(--z-toast);
  padding: 4px 12px;
  border-radius: var(--md-sys-shape-corner-full);
  font-size: var(--md-sys-typescale-label-small-size);
  font-weight: var(--md-sys-typescale-label-small-weight);
  opacity: 0;
  transform: translateY(-12px);
  transition: opacity var(--md-sys-duration-medium2) var(--md-sys-motion-easing-emphasized-decelerate),
              transform var(--md-sys-duration-medium2) var(--md-sys-motion-easing-emphasized-decelerate);
  pointer-events: none;
  letter-spacing: var(--md-sys-typescale-label-small-tracking);
}

.connection-status.show { opacity: 1; transform: translateY(0); }

.connection-status.online {
  background: var(--md-sys-color-primary-container);
  color: var(--md-sys-color-on-primary-container);
}
.connection-status.offline {
  background: var(--md-sys-color-error-container);
  color: var(--md-sys-color-on-error-container);
  animation: pulse 2s var(--md-sys-motion-easing-standard) infinite;
}
.connection-status.connecting,
.connection-status.reconnecting {
  background: var(--md-sys-color-secondary-container);
  color: var(--md-sys-color-on-secondary-container);
  animation: pulse 1.5s var(--md-sys-motion-easing-standard) infinite;
}

/* ---- MD3 Snackbar (Toast) ---- */
.toast-notification {
  position: fixed;
  top: 12px;
  left: 50%;
  transform: translateX(-50%) translateY(-120%);
  z-index: var(--z-toast);
  padding: 10px 20px;
  border-radius: var(--md-snackbar-container-shape);
  font-size: var(--md-sys-typescale-body-medium-size);
  font-weight: var(--md-sys-typescale-label-large-weight);
  opacity: 0;
  transition: transform var(--md-sys-duration-medium3) var(--md-sys-motion-easing-emphasized-decelerate),
              opacity var(--md-sys-duration-medium1) var(--md-sys-motion-easing-standard);
  pointer-events: none;
  max-width: calc(100% - 32px);
  text-align: center;
  box-shadow: var(--md-snackbar-container-elevation);
}

.toast-notification.show {
  transform: translateX(-50%) translateY(0);
  opacity: 1;
}

.toast-notification.toast-success {
  background: var(--md-sys-color-primary-container);
  color: var(--md-sys-color-on-primary-container);
}
.toast-notification.toast-error {
  background: var(--md-sys-color-error-container);
  color: var(--md-sys-color-on-error-container);
}
.toast-notification.toast-info {
  background: var(--md-sys-color-tertiary-container);
  color: var(--md-sys-color-on-tertiary-container);
}

/* ---- Animations ---- */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes messageSlideIn {
  from { opacity: 0; transform: translateY(8px) scale(0.96); }
  to { opacity: 1; transform: translateY(0) scale(1); }
}
@keyframes spin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}
@keyframes shimmer {
  0% { background-position: -200px 0; }
  100% { background-position: calc(200px + 100%) 0; }
}
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}
@keyframes slideUp {
  from { opacity: 0; transform: translateY(100%); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes slideDown {
  from { opacity: 0; transform: translateY(-20px); }
  to { opacity: 1; transform: translateY(0); }
}

.fade-in {
  animation: fadeIn var(--md-sys-duration-medium2) var(--md-sys-motion-easing-emphasized-decelerate);
}
.message-fade-in {
  animation: messageSlideIn var(--md-sys-duration-medium3) var(--md-sys-motion-easing-emphasized-decelerate);
}

/* ---- Top Loading Indicator (MD3 Linear Progress) ---- */
.top-loading-indicator {
  text-align: center;
  padding: 8px;
  font-size: var(--md-sys-typescale-label-small-size);
  color: var(--md-sys-color-outline);
  animation: fadeIn var(--md-sys-duration-medium1) var(--md-sys-motion-easing-standard);
}

/* ---- Date Separator ---- */
.date-separator {
  text-align: center;
  padding: 12px 0 8px;
  font-size: var(--md-sys-typescale-body-small-size);
  color: var(--md-sys-color-outline);
  position: relative;
}

.date-separator::before,
.date-separator::after {
  content: "";
  position: absolute;
  top: 50%;
  width: calc(50% - 64px);
  height: 1px;
  background: var(--md-sys-color-outline-variant);
}
.date-separator::before { left: 0; }
.date-separator::after { right: 0; }

.date-separator span {
  background: var(--md-sys-color-surface);
  padding: 0 12px;
  font-weight: var(--font-weight-medium);
}

/* ---- MD3 Divider ---- */
.md-divider {
  height: var(--md-divider-thickness);
  background: var(--md-divider-color);
  border: none;
  margin: 8px 0;
}